This invention relates to liquid spray nozzles and, more particularly, to liquid spray nozzles particularly suitable for use in internal combustion engines.
Increasing environmental concerns have resulted in numerous attempts to design spray nozzles for use in fuel injection systems in internal combustion engines that have a so-called "zero sac" volume or wherein the sac volume is minimized. In many prior art constructions, a small volume exists between the fuel flow control, usually a valve, and the outlet of the injection nozzle. After fuel has been injected through the nozzle, liquid fuel will remain within the small volume and will not participate in the combustion process. At later stages of the combustion cycle, the proximity of such liquid fuel to the hot gases of combustion will cause the fuel to vaporize, but since it is not oxidized, it is exhausted from the engine as a hydrocarbon emission.
To minimize the problem, it has been proposed to utilize extremely fine slots in fuel injection nozzles, the sides of which are permanently spaced from each other by a small amount, normally not more than about 0.001 inches or less. As a consequence, there is a sac volume, so the problem is only minimized, not eliminated.
Of further significance is the fact that such narrow slots are extremely difficult to form and the formation of the same to some desired standard of reproducibility requires expensive and complex forming operations.